Apparatus for production of a closed tube of semiconductor material

ABSTRACT

An apparatus comprised of a housing member having an inner hollow chamber, a pair of electrically conductive mounting members electrically insulated from each other and positioned within the chamber, a carbon rod member mounted on one of the mounting members and a carbon tube member mounted on the other of the mounting members concentrically about the rod member, a carbon cap member joining the rod and tube members at their upper surfaces to provide a substantially continuous smooth exterior surface for formation of a tube thereon, means for feeding a gaseous material which includes a semiconductor material into the chamber, means for withdrawing a residual gas from the chamber and means for supplying energy to the mounting means so that the exterior surfaces of the tube member and cap member are uniformly heated and a desired tube closed at one end thereof forms about such heated carbon surfaces.

United States Patent 1 Dietze APPARATUS FOR PRODUCTION OF A CLOSED TUBEOF SEMICONDUCTOR MATERIAL [111 3,747,559 July 24, 1973 PrimaryExaminer-Morris Kaplan Attorney-Benjamin H. Sherman, J. Arthur Gross eta1.

[57] ABSTRACT An apparatus comprised of a housing member having an innerhollow chamber, a pair of electrically conductive mounting memberselectrically insulated from each other and positioned within thechamber, a carbon rod member mounted on one of the mounting members anda carbon tube member mounted on the other of the mounting membersconcentrically about the rod member, a carbon cap member joining the rodand tube members at their upper surfaces to provide a substantiallycontinuous smooth exterior surface for formation of a tube thereon,means for feeding a gaseous material which includes a semiconductormaterial into the chamber, means for withdrawing a residual gas from thechamber and means for supplying energy to the mounting means so that theexterior surfaces of the tube member and cap member are uniformly heatedand a desired tube closed at one end thereof forms about such heatedcarbon surfaces.

10 Claims, 3 Drawing Figures APPARATUS FOR PRODUCTION OF A CLOSED TUBEOF SEMICONDUCTOR MATERIAL BACKGROUND OF THE DISCLOSURE 1. Field of theInvention The invention relates to the production of tubes composed ofsemiconductor materials and more particularly to an apparatus forproducing a tube open at only one end thereof having substantiallyuniform wall thicknesses and composed of a semiconductor material.

2. Prior Art Apparatus for the production of a tube open at only one endthereof and composed of a semiconductor material is known, for example,see Gennan Offenlegungsschrift 1,805,970. The prior art apparatusincludes a heated tube carrier member comprised of an outer cylindricalmember and an inner metallic rod member. The rod member is composed ofiron and during operation, heat is not uniformly transferred to theexterior surface of the cylindrical member. In fact, the temperature atthe upper closed end of the cylindrical member is much lower than otherportions thereof. Accordingly, the deposition of semiconductor materialstakes place much slower on the low temperature areas of the cylindricalmember. Further, the uniformity of the wall thickness of the producedtubes of semiconductor material is adversely effected by the nonuniformheat distribution on the surfaces of the cylindrical member.

SUMMARY OF THE INVENTION The invention provides an apparatus forproducing a tube closed at one end thereof composed ofa semiconductormaterial and having a substantially uniform wall thickness throughoutthe extent thereof.

The invention includes an apparatus having a tube carrier meanscomprised of an outer cylindrical carbon tube member and an inner carbonrod member joined together at their upper surfaces by a carbon capmember to provide electrical continuity between the tube and rod membersand provide a smooth exterior surface for deposition of a desired closedtube of semiconductor material. Electricity supplied to the cylindricaltube and rod member cause uniform heating of all other surfaces of thetube carrier means so that a uniform deposition of semiconductormaterial takes place thereon. Preferably, the cylindrical tube, innerrod and cap members are composed of a carbon material selected from thegroup consisting of vitreous carbon, spectral carbon and pyrolyticgraphite.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevated cross-sectionalview of an apparatus embodiment of the invention;

FIG. 2 is a partial enlarged cross-section view of a portion of anapparatus constructed in accordance with the principles of theinvention; and

FIG. 3 is a view somewhat similar to that of FIG. 2 illustrating anotherembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention provides anapparatus for producing a closed tube of semiconductor material having asubstantially uniform wall thickness over its entire surface.

The invention utilizes a tube carrier means that includes an inner rodcomposed of a material having a relatively high specific electricalresistance and a high heat conductivity so that the tube carrier meansis uniformly heated over its entire surface for uniform deposition of asemiconductor material on its peripheral surface.

Perferably, the inner rod member is composed of a carbon materialselected from the group of vitreous carbon (a carbon produced fromsynthetic organic materials heated in the absence of air), spectralcarbon (a highly purified carbon extracted from coal and carbonized atabout 3000 C.) and pyrolytic graphite. Such carbon materials areuniformly heated and, as opposed to metallic materials such as iron orcopper, are not attacked by gaseous components of semiconductormaterials at elevated temperatures.

In accordance with the principles of the invention, the amount of heattransfer between the inner rod member and surrounding cylindrical memberis readily regulated. The rod member mates with a concentric recess inthe upper end surface of the cylindrical member. In certain embodimentsmatching thread means are provided between adjoining surfaces of the rodand cylindrical members so that the amount of surface contact betweensuch members is easily regulated by increasing or decreasing the amountof thread contact. In other embodiments, the rod member is provided withan upper cap portion having fitted or machined surfaces in press-fitcontact with adjacent surfaces of the cylindrical member so that theamount of contact between such fitted surfaces and cylindrical membersurface is easily regulated by regulating the amount of insertion of thecap portion within the cylindrical member.

It is preferable to provide a separate cap member for joining the innerrod member to the cylindrical member, although, as will be appreciated,the rod member may be formed having a suitable upper portion snuglyfitting within the cylindrical member. In one embodiment, the cap memberis provided! with threads along a dependent portion thereof for securingthe same to a threaded recess within the upper end of a rod member andhas side flange surfaces contacting the end surfaces of a cylindricalmember. In another embodiment, the cap member is provided with amachined recess for receiving the upper end portion of the rod membertherein and has machined side surfaces for snugly fitting within theinner walls of the cylindrical member. In either form, the cap memberprovides a substantially smooth exterior surface along the upper portionof the cylindrical member. A desired semiconductor material isdeposited, as from a gaseous compound thereof, onto the exterior surfaceof the tube carrier means until a desired wall thickness is attained andis then readily removed from the carrier member.

In one specific embodiment, a hollow cylindrical member having a closedupper end is provided with a centralized bore through its upper end andan upper end of a rod member is concentrically mounted within thecylindrical member and snugly mated with the bore so that there iselectrical and mechanical contact between the rod and cylindricalmember. The upper end of the rod member is provided with a centralizedbore and a cap member is suitably secured thereto. The cap member ispreferably mushroomed-shaped and has a stem portion that mates with thebore in the rod member and a cap portion of an outer diameter issubstantially equal to the outer diameter of the cylindrical member. Thestem portion and bore walls may be provided with matching threads forinterlocking the cap member onto the rod member or the stem portion maybe provided with machined surfaces for press-fit securement within therod. The cap member provides a smooth end surface for the deposition ofsemiconductor materials thereon.

In another specific embodiment, a hollow cylindrical member is properlypositioned in an operational environment and a solid rod memberconcentrically mounted thereon out of contact with the cylindricalmember. A suitably shapedcap member is secured onto the rod member andonto the cylindrical member to provide electrical contact therebetween.The cap member is preferably provided with a centralized recess havingmachined side walls for snugly fitting onto the upper end of the rodmember and with machined outer side surfaces for snugly fitting withinthe upper end of the cylindrical member.

The cap member is selectively movable in its operational position forvarying the amount of surface contact between the components of the tubecarrier means, i.e. the rod member, the cylindrical member and the capmember.

Referring now to the drawing, FIG. 1 illustrates an exemplary embodimentof an apparatus suited for the practice of the invention. A housingmember 1 having a relatively large hollow inner chamber la is sealedfrom ambient environment by a bottom plate member 2. The chamber 1awithin housing member 1 is substantially gas-impervious. Gas feed tubes4 are provided through plate member 2 to allow the introduction of asuitable gaseous compound of a semiconductor material (i.e., SiHCl and asuitable reaction gas (i.e., H into the chamber. As shown, tubes 4 aresurrounded by further tubes 5. Residual gases (i.e., HCl) are withdrawnfrom the chamber la by vacuum or the like via tubes 5.

A pair of electrical conduits 7, (such as silver electrodes) areprovided through plate member 2 and sealed by sealing means 6, as of afluoroplastic material such as tetrafluoroethylene. The conduits 7 areoperationally connected to a suitable source of electricity (not shown).

A pair of mounting block members 8 and 9 are positioned within thechamber la in an electrically insulated relation to each other and eachin an electrically conductive relation with one of the pair of conduits7. The blocks 8 and 9 are composed of an electrically conductivematerial, such as graphite.

A tubular or cylindrical member 11 is mounted onto block member 8 andextends upwardly therefrom within the chamber la. The tubular member 11is hollow and includes at least a partial upper end surface. Member 11is preferably composed of a carbon material selected from the group ofvitreous carbon, spectral carbon and pyrolytic graphite.

A rod member 10 is mounted onto block member 9 and concentrically withinthe cylindrical member 11. The rod member 10 substantially extendsthroughout the entire length of cylindrical member 11 and is secured atits upper end to an adjacent end surface of member 11. Rod member 11 ispreferably composed of a carbon material selected from the group ofvitreous carbon, spectral carbon and pyrolytic graphite.

In the embodiment illustrated at FIG. 1, the adjacent surfaces of theupper end of rod member 10 and upper end of cylindrical member 11 areprovided with matching thread means 12. The thread means 12 provide amechanical and electrical connection between members l0 and 11.

During operation, a suitable voltage is supplied to electrical conduits7 from a suitable source. The conduits 7 conduct this energy via blockmembers 8 and 9 to members 10 and 11 respectively, ,so as to heat thesame. The rod member 10 thus emits heat upwardly, by conductivity andradially by radiation so that particularly the upper surfaces ofcylindrical member 11 are heated to a temperature approximately equal tothe temperature of its remaining surfaces. The beneficial effects of rodmember 10 are further improved by interlocking thread means 12 at theupper ends of members l0 and 11. The contact resistance between membersl0 and 11 increases with increased thread contact so that electricalenergy is transformed into heat at the contact area in proportion to theincreased resistance in accordance with the Ohm law. The temperatureprofile over the length of member 11 is thus readily controlled byincreasing or decreasing the thread contact between the upper ends ofmembers 10 and 11. Any desired surface contact adjustment is effectedbefore tube producing operations are begun and before the semiconductormaterial is deposited.

in preferred embodiments, a cap member 13 is mounted onto the member 11so that a completely planar peripheral surface is provided for thesemiconductor material being deposited thereon. In order to secure capmember 13 to member 11 it is preferable to provide a thread means 14 forinterlocking the cap member 13 to member 10 and to member 11. In orderto accomplish this, member 10 is provided with a recess on its upper endsurface having threads along the side surfaces thereof. Cap member 13 isprovided with a stem portion having matching threads on the sidesurfaces thereof for interlocking with the threads in the recess of rodmember 10. The cap member 13 also has radially extending side flangesurfaces which overlie the end surfaces of member 11 so that when thecap member is securely threaded onto the rod member 10 the entireassemblage of member 10, member 11 and member 13 forms a unitary tubecarrier means.

The technique for depositing a desired closed tube 15 composed of asemiconductor material is well known and quite similar to the techniquefor producing rods composed of semiconductor materials. Accordingly, nofurther aspect of the method of depositing semiconductor materials arenecessary. As an exemplary form of suitable materials, silico-chloroform(SiHCl is utilized as a gaseous semiconductor component and hydrogen (His utilized as a reaction gas. The gaseous mixture is fed into thechamber 1a via tubes 4 and the outer surface of the tube carrier meansis heated to a temperature in the range of about 11,000 to l2,500 C. andpreferably 1 1,500 C. so that deposition of, for example, silicon, ontothe heated surface occurs.

FIG. 2 illustrates the upper portion of a tube carrier means comprisedof an outer hollow cylindrical member 11, an inner rod member 10 and acap member 13. Thread means 12 and 14 are provided respectively betweenthe adjacent side surfaces of members 10 and 11 and between adjacentsurfaces of members 10 and 13.

The contact resistance is regulated by controlling the thread contactbetween such members.

FIG. 3 illustrates a similar upper portion of another embodiment of atube carrier means comprised of a hollow cylindrical member 11, aconcentrically mounted rod member and a cap member 16. The cap member 16is provided with machined or fitted surfaces 17 dimensioned so as topress-fit into the open end of member 11. Similarly, cap member 16 isprovided with a down-facing recess with machined side surfaces 18 for apress-fit onto the end of rod member 10. In this embodiment, there is ahigh contact resistance between the members 10 and 11 at machinedsurfaces 17 and 18. Accordingly, the temperature of the end surface ofsuch a tube carrier means is further increased so that a substantiallyuniform. deposition of a semiconductor material is attained over theentire surface of the tube carrier means. Of course, the contactresistance is readily adjusted by regulating the amount of contactbetween the pres-fit surfaces.

The means for limiting the amount of contact between members 10 and 11are selected as desired. For example, the embodiment illustrated at FIG.2 can be modified to use machined surfaces between thevarious componentsof the tube carrier means and the embodiment shown at FIG. 3 can bemodified to use thread means between the various components of the tubecarrier means. Also, the invention encompasses embodiments utilizingtube carrier means having both machined surfaces and thread means forregulating the amount of contact between the respective members thereof.

As is apparent from the foregoing specification, the present inventionis susceptible of being embodied with various alterations andmodifications which may differ particularly from those that have beendescribed in the preceding specification and description. For thisreason, it is to be fully understood that allof the foregoing isintended to be merely. illustrative andis not to be construed orinterpredeted as being restrictive or 0therwise limiting of the presentinvention, excepting as is set forth and defined inthe hereto-appendantclaims.

"I claim as my invention:

1. An apparatus for producing tubes closed at one end thereof andcomposed of a semiconductor material comprising;

a gas-impermeable. housing member having tively large inner chamber;

a pair of electrically conductive mounting members electricallyinsulated from each other and. positioned within said inner chamber;

an electrically conductive closed and "tube carrier means having asubstantially smooth continuous outer surface mounted within said innerchamber and in working relation on said mounting members; said tubecarrier means including a hollow cylindrical member mounted on one ofsaid pair of mounting members and a rod member mounted on the other ofsaid pair of mounting members and concentrically within said hollowcylindrical member and connected to said closed end; means for feedingand withdrawing a gaseous material to and from said inner chamber; andmeans for supplying electrical energy to said cylindria rela- 6 calmember and rod member vla said pair of mounting members forsubstantially uniform heat ing of the outer surface of said tube carriermeans.

2. An apparatus as defined in claim 1 wherein the cylindrical memberincludes a centralized recess at an outer upper end surface portionthereof, said recess defining cylindrical inner side surface portions;and the rod member includes an outer upper end surface portion in snugcontact with said cylindrical inner side surface portions.

3. An apparatus as defined in claim 1 wherein the closed end includes acap member securely mounted onto the outer upper end surface portion ofthe rod member and in snug contact with cylindrical inner side surfaceportions of the cylinder member, said cap and rod members beingrelatively movable for varying the surface contact between saidcylindrical member, rod member and cap member.

4. An apparatus as defined in claim 2 wherein the closed end includes acap member having a stem portion with outer stem side surface portionsand the rod member includes a centralized recess at the outer upper endsurface portions thereof, said recess defining rod recess inner sidesurface portions, said outer stem side surface portions being in snugcontact with said rod recess inner side surface portions.

5. An apparatus as defined in claim 4 wherein the outer stern sidesurface portions of the capmember and the rod recess inner side surfaceportions of the rod member are provided with matching thread means forthread securement of the capmember to the rod member.

6. An apparatus as defined in claim 4 wherein the outer stem sidesurface portions of the cap member and the rod recess inner side surfaceportions of the rod member are provided withmatching machined surfacesfor press-fit securement of the cap member to the rod member.

7. An apparatus as defined in claim 3 wherein the cap member includes acentralized recess at an outer lower surface portion thereof, saidrecess defining cap recess inner side surface portions, said cap memberincluding outer side surface portions, said cap recess inner sidesurface portions being in snug contact with the outer upper end surfaceportions of the rod member and said outer side sur-face portions of thecap member being in snug contact withthe cylindricalinner side surfacesof the cylindrical member.

8. An apparatus as defined in claim 7 wherein the cap recess inner sidesurface portions, the outer upper end surface portions of the rodmember, the outer side surface portions of the cap member and thecylindrical inner side surfaces of the cylindrical member are providedwith matching thread means for thread securement of said members to oneanother. I

9. An apparatus as defined in claim 7 wherein the cap recess inner sidesurface portions, the outer upperend surface portions of the rod member,the outer side surface portions of the cap member and the cylindricalinner side surfaces of the cylindrical member are providedwith matchingmachined surfaces for press-fit securement of said members to oneanother;

10. An apparatus for producing tubes closed at one end thereof andcomposed of a semicomductor material comprising;

a gas-impermeable housing means having-a relatively large inert chamber;

a pair of electrically conductive mountingmembers electrically insulatedfrom each other and positioned within said inner chamber;

a tube carrier means having a substantially smooth continuous outersurface mounted in working relation on said mounting members; said tubecarrier means comprising: a hollow cylindrical member mounted on one ofsaid pair of mounting members, a rod member mounted on the other of saidpair of mounting members and concentrically within said hollowcylindrical member out of contact therewith, and a cap membermechanically and electrically interlocking the rod member with thecylindrical member, said cap member being relatively movable foruniformly heat the outer surface thereof.

1. An apparatus for producing tubes closed at one end thereof andcomposed of a semiconductor material comprising; a gas-impermeablehousing member having a relatively large inner chamber; a pair ofelectrically conductive mounting members electrically insulated fromeach other and positioned within said inner chamber; an electricallyconductive closed and tube carrier means having a substantially smoothcontinuous outer surface mounted within said inner chamber and inworking relation on said mounting members; said tube carrier meansincluding a hollow cylindrical member mounted on one of said pair ofmounting members and a rod member mounted on the other of said pair ofmounting members and concentrically within said hollow cylindricalmember and connected to said closed end; means for feeding andwithdrawing a gaseous material to and from said inner chamber; and meansfor supplying electrical energy to said cylindrical member and rodmember via said pair of mounting members for substantially uniformheating of the outer surface of said tube carrier means.
 2. An apparatusas defined in claim 1 wherein the cylindrical member includes acentralized recess at an outer upper end surface portion thereof, saidrecess defining cylindrical inner side surface portions; and the rodmember includes an outer upper end surface portion in snug contact withsaid cylindrical inner side surface portions.
 3. An apparatus as definedin claim 1 wherein the closed end includes a cap member securely mountedonto the outer upper end surface portion of the rod member and in snugcontact with cylindrical inner side surface portions of the cylindermember, said cap and rod members being relatively movable for varyingthe surface contact between said cylindrical member, rod member and capmember.
 4. An apparatus as defined in claim 2 wherein the closed endincludes a cap member having a stem portion with outer stem side surfaceportions and the rod member includes a centralized recess at the outerupper end surface portions thereof, said recess defining rod recessinner side surface portions, said outer stem side surface portions beingin snug contact with said rod recess inner side surface portions.
 5. Anapparatus as defined in claim 4 wherein the outer stem side surfaceportions of the cap member and the rod recess inner side surfaceportions of the rod member are provided with matching thread means forthread securement of the cap member to the rod member.
 6. An apparatusas defined in claim 4 wherein the outer stem side surface portions ofthe cap member and the rod recess inner side surface portions of the rodmember are provided with matching machined surfaces for press-fitsecurement of the cap member to the rod member.
 7. An apparatus asdefined in claim 3 wherein the cap member includes a centralized recessat an outer lower surface portion thereof, said recess defining caprecess inner side surface portions, said cap member including outer sidesurface portions, said cap recess inner side surface portions being insnug contact with the outer upper end surface portions of the rod memberand said outer side sur-face portions of the cap member Being in snugcontact with the cylindrical inner side surfaces of the cylindricalmember.
 8. An apparatus as defined in claim 7 wherein the cap recessinner side surface portions, the outer upper end surface portions of therod member, the outer side surface portions of the cap member and thecylindrical inner side surfaces of the cylindrical member are providedwith matching thread means for thread securement of said members to oneanother.
 9. An apparatus as defined in claim 7 wherein the cap recessinner side surface portions, the outer upper end surface portions of therod member, the outer side surface portions of the cap member and thecylindrical inner side surfaces of the cylindrical member are providedwith matching machined surfaces for press-fit securement of said membersto one another.
 10. An apparatus for producing tubes closed at one endthereof and composed of a semicomductor material comprising; agas-impermeable housing means having a relatively large inert chamber; apair of electrically conductive mounting members electrically insulatedfrom each other and positioned within said inner chamber; a tube carriermeans having a substantially smooth continuous outer surface mounted inworking relation on said mounting members; said tube carrier meanscomprising: a hollow cylindrical member mounted on one of said pair ofmounting members, a rod member mounted on the other of said pair ofmounting members and concentrically within said hollow cylindricalmember out of contact therewith, and a cap member mechanically andelectrically interlocking the rod member with the cylindrical member,said cap member being relatively movable for varying the surface contactbetween said cylindrical member, rod member and cap member, said tubecarrier means being composed of a carbon material selected from thegroup of vitreous carbon, spectral carbon and pyrolytic graphite; meansfor feeding with withdrawing a gaseous material to and from said innerchamber; and means for supplying electrical energy to said tube carriermeans via said pair of mounting members to uniformly heat the outersurface thereof.